The authors present an unusual case report of a 32-year-old man with advanced allergic fungal sinusitis, presenting with severe bilateral visual loss and restricted ocular motility. On presentation he had an 18 month history of progressive nasal obstruction, as well as several months of diminished visual acuity. On examination he had counting fingers vision in his right eye and 6/9 in the left. He had proptosis of 27mm in the right eye and 25mm in the left. Eye movements were restricted bilaterally. Humphrey visual fields revealed globally depressed fields in the right eye and a temporal hemianopia with paracentral nasal scotomas in the left eye. This patient was treated with prednisolone as well as sinus surgery and as a result he showed improvements in his visual acuity, ocular motility and visual fields. Ophthalmic manifestations from this disease are rare but can occur in advanced disease and allergic fungal sinusitis must therefore be considered as a diagnosis by ophthalmologists. In such cases, early recognition, neuroimaging for optic nerve involvement and prompt ENT interventions are crucial to reduce visual loss.